Cylinder liner and cylinder block

摘要

A cast iron cylinder liner (10) of the present invention includes a plurality of grooves (15) formed on an outer surface (12) of the cylinder liner (10). Each of the grooves (15) extends in a circumferential direction (R) of the cylinder liner (10) in a ring or helical shape, and the grooves (15) divide the outer surface (12) of the cylinder liner (10) into a plurality of ring or helical sections (14). The outer surfaces of the ring sections (14) have a uniform distance from the central axis (L) of the cylinder liner (10) over the entire area of the outer surfaces, and the grooves (15) are arranged symmetrically with respect to the center of the cylinder liner (10) in an axial direction thereof. Each of the grooves (15) has a J-shaped longitudinal cross-section including a first inclination part (15b) and a groove bottom part (15d). The first inclination part (15f) extends from the outer surface of one of the ring sections (14) or of one turn of the helical sections toward the center of the cylinder liner (10) in an axial direction thereof. The groove bottom part (15d) has a longitudinal cross-section approximately in the form of a circular arc, and extends from the first inclination part (15b) in a direction away from the center of the cylinder liner (10) in an axial direction thereof.